在配置单元上交叉应用SQL Server查询

Question

HDP-2.5.0.0使用Ambari 2.4.0.1

配置单元表ReportSetting如下所示：

id int
serializedreportsetting String

"serializedreportsetting"列是源SQL Server数据库中的XML数据类型，但在Sqoop导入过程中转换为String，这就是它在SQL Server中的样子：

<ReportSettings4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Trigger>
  <Manual>true</Manual>
  </Trigger>
<StartTime>
    <Year>8</Year>
    <Month>1</Month>
    <Day>1</Day>
    <Hour>0</Hour>
    <Minute>0</Minute>
  </StartTime>
  <ReportPeriod>
    <Month>0</Month>
    <Day>0</Day>
    <Hour>0</Hour>
    <Minute>5</Minute>
  </ReportPeriod>
  <Theft>
    <DigitalInput>true</DigitalInput>
    <Can>false</Can>
  </Theft>
  <SequenceNo>0</SequenceNo>
</ReportSettings4>

在配置单元表中：

<ReportSettings4 xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Trigger><Manual>true</Manual></Trigger><StartTime><Year>8</Year><Month>12</Month><Day>31</Day><Hour>23</Hour><Minute>34</Minute></StartTime><ReportPeriod><Month>0</Month><Day>0</Day><Hour>4</Hour><Minute>0</Minute></ReportPeriod><Theft><DigitalInput>false</DigitalInput><Can>false</Can></Theft><SequenceNo>3</SequenceNo></ReportSettings4>

在SQL Server上运行良好的查询：

SELECT
r.VehicleId
,rs.value('(Trigger/Manual)[1]', 'bit') AS RS_Trigger_Manual, ,CAST(CONCAT(CASE WHEN rs.value('(StartTime/Year)[1]', 'int') < 10 THEN CONCAT('200',rs.value('(StartTime/Year)[1]', 'int')) ELSE CONCAT('20',rs.value('(StartTime/Year)[1]', 'int')) END,'-',rs.value('(StartTime/Month)[1]', 'int'),'-',rs.value('(StartTime/Day)[1]', 'int'),' ',rs.value('(StartTime/Hour)[1]', 'int'),':',rs.value('(StartTime/Minute)[1]', 'int'),':','00.000') AS datetime) AS RS_StartTime
,rs.value('(ReportPeriod/Month)[1]', 'int') AS RS_ReportPeriod_Month
,rs.value('(ReportPeriod/Day)[1]', 'int') AS RS_ReportPeriod_Day
,rs.value('(ReportPeriod/Hour)[1]', 'int') AS RS_ReportPeriod_Hour
,rs.value('(ReportPeriod/Minute)[1]', 'int') AS RS_ReportPeriod_Minute
,rs.value('(Theft/DigitalInput)[1]', 'bit') AS RS_Theft_DigitalInput
,rs.value('(Theft/Can)[1]', 'bit') AS RS_Theft_Can,rs.value('(SequenceNo)[1]', 'int') 
AS RS_SequenceNo FROM ReportSetting r
  CROSS APPLY SerializedReportSetting.nodes('/*') AS ReportSettings(rs)

我可以考虑/做以下事情：

1. 要使用CROSS APPLY，我想需要使用横向视图，这里我没有将serializedportsetting作为数组，所以explode((不起作用。有人能验证我是否朝着正确的方向思考吗

2. 我只是尝试使用内置的xpath-udf将serializedportsetting中的数据获取为列，然而，我没有得到任何记录，一些尝试如下：

   从ReportSetting限制1中选择xpath(SerializedReportSetting，'/*'(；

   从ReportSetting限制1中选择xpath(SerializedReportSetting，'/ReportSettings4'(；

   从ReportSetting限制1中选择xpath(SerializedReportSetting，'/Trigger/Manual'(；

**********更新-1**********

我使用regexp_replace来处理上述挑战：

SELECT id,
  xpath_string(SerializedReportSetting,'/ReportSettings/Trigger/Manual')        AS RS_Trigger_Manual,
  xpath_string(SerializedReportSetting,'/ReportSettings/Trigger/DriveChange')   AS RS_Trigger_DriveChange
FROM
  (SELECT id,
    regexp_replace(SerializedReportSetting, 'ReportSettings+\d','ReportSettings') AS SerializedReportSetting
  FROM reportsetting
  WHERE id IN (1701548,3185,1700231,1700232)
  ) reportsetting_regex;

Answer 1

在xpath中，他们明确表示：

xpath()函数总是返回一个字符串的配置单元数组。如果表达式产生非文本值(例如，另一个xml节点(，则函数将返回一个空数组

因此，您可以使用：xpath(SerializedReportSetting,'/ReportSettings4/Trigg‌​er/Manual/text()') from ReportSetting limit 1;

或者更好的选择是使用xpath_boolean/xpath_int:

xpath_boolean-如果XPath表达式的计算结果为true，或者找到匹配的节点，则返回true。

xpath_boolean(SerializedReportSetting,'/ReportSettings4/Trigg‌​er/Manual') from ReportSetting limit 1;

xpath_short、xpath_int、xpath_long这些函数返回一个整数值，如果未找到匹配项，则返回值零，或者找到匹配项但该值不是数字。支持数学运算。如果值溢出返回类型，则返回该类型的最大值。

xpath_int(SerializedReportSetting,'/ReportSettings4/ReportPeriod/Month') from ReportSetting limit 1;